Analysis of the evolutionary history of the nAChR family with chromosomal locations of the nAChR genes and their neighboring gene families in human, chicken and spotted gar. Crosses indicate gene loss or gene not yet identified. Chicken and spotted gar illustrations are re-used with permission from Daniel Ocampo Daza, source: www.egosumdaniel.se and the human image is re-used with permission from https://commons.wikimedia.org. The duplication scheme and neighboring gene families for the CHRNA9/CHRNA10 genes. The right panel summarizes chromosomes included. This paralogon is referred to as paralogon 3 in this study.